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Home › Saturn › 2001 › SC2 Automatic, MP6 › Repair and Diagnosis › Engine Performance › System › Engine Control System - System Testing & Engine Component Tests › Engine Sensors & Switches › Manifold Absolute Pressure Sensor › 3.1L (Lumina)

3.1L (Lumina)

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing powertrain diagnostic system check, go to next step.
  2. Check for the following conditions:
    • MAP sensor seal damaged or missing.
    • Vacuum hoses disconnected, damaged or incorrectly routed.
    • Intake manifold vacuum leaks.
    • Vacuum leak at throttle body.
    • Vacuum leaks in EGR system.
    • Faulty PCV system.
    If problem does not exist, go to next step. If problem exists, repair as necessary. After repairs, go to step  14.
  3. Disconnect MAP sensor harness connector. Turn ignition on, engine off. Using scan tool, observe MAP sensor parameter. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step  12.
  4. Connect a 3-amp fused jumper wire between MAP sensor signal circuit (Light Green wire) and MAP sensor reference voltage circuit (Gray wire) at MAP sensor harness connector. Turn ignition on, engine off. Observe MAP sensor parameter. If scan tool displays 4.95 volts, go to next step. If scan tool does not display 4.95 volts, go to step  8.
  5. Using test light connected to battery voltage, probe MAP sensor signal circuit (Light Green wire) at MAP sensor harness connector. Observe MAP sensor parameter. If scan tool displays 4.95 volts, go to next step. If scan tool does not display 4.95 volts, go to step  9.
  6. Turn ignition off. Check for faulty MAP sensor harness connections. If connections are okay, go to next step. If connections are not okay, repair as necessary. After repairs, go to step  14.
  7. Check for open or high resistance in MAP sensor ground circuit (Orange/Black wire). If ground circuit is okay, go to step  11. If ground circuit is not okay, repair as necessary. After repairs, go to step  14.
  8. Check for open or high resistance in MAP sensor 5 volt reference circuit (Gray wire). If MAP sensor 5 volt reference circuit is okay, go to step  10. If MAP sensor 5 volt reference circuit is not okay, repair as necessary. After repairs, go to step  14.
  9. Check for open, short to ground or short to sensor ground circuit (Orange/Black wire) in MAP sensor signal circuit (Light Green wire). If MAP sensor signal circuit is okay, go to next step. If MAP sensor signal circuit is not okay, repair as necessary. After repairs, go to step  14.
  10. Check for poor MAP sensor signal circuit connection at PCM. If connection at PCM is okay, go to next step. If connection at PCM is not okay, repair as necessary. After repairs, go to step  14.
  11. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Check for short to voltage in MAP sensor reference voltage circuit (Gray wire). If short to voltage does not exist, go to next step. If short to voltage exists, repair as necessary. After repairs, go to step  14.
  12. Replace MAP sensor. If system is repaired, go to step  14. If system is not repaired, go to next step.
  13. Replace PCM. After repairs, go to next step.
  14. Start engine and idle. While observing MAP sensor parameter on scan tool, increase engine RPM. If MAP sensor valve changes, system is okay. If MAP sensor valve does not change, go to step  2.
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